#To-do: 1. Snowcover effects on clp abund for all lakes where the DB has multiple CLP projects - non-local winter data -

  1. Compare my results to old ones! Lake past, neighbors, watershed, state?

Prep WS

#load libraries
library(data.table)
library(tidyr)
library(stringr)
library(ggplot2)
library(plotly)
## 
## Attaching package: 'plotly'
## The following object is masked from 'package:ggplot2':
## 
##     last_plot
## The following object is masked from 'package:stats':
## 
##     filter
## The following object is masked from 'package:graphics':
## 
##     layout
#import Data
surveys <- fread("scripts&data/data/input/lake_year_data.csv")
rawdata <- fread("scripts&data/data/input/PCRIsurveysPICharter2srt_sheet1rawdata.csv")

#data explore

#see if we can re-generate ray's calc'd CLP values
# summary(rawdata)
  rawdata[ , .N , .(SURVEY_START, DOW) ]
##      SURVEY_START      DOW     N
##            <char>    <int> <int>
##   1:    6/25/2008  1000100    85
##   2:    6/18/2012  1010400    34
##   3:     6/8/2011  1010500    80
##   4:    5/24/2010  1014200   216
##   5:    6/21/2012  1014900    43
##  ---                            
## 956:    6/20/2005 86023400   181
## 957:    6/25/2017 86025200   836
## 958:    6/27/2013 86025500    39
## 959:    4/22/2017 86026400   158
## 960:    6/20/2007 86047000    33
  names(rawdata)[str_detect(names(rawdata), "pota")]
##  [1] "potamogeton_crispus"        "potamogeton_amplifolius"   
##  [3] "potamogeton_foliosus"       "potamogeton_pusillus"      
##  [5] "potamogeton_robbinsii"      "potamogeton_zosteriformis" 
##  [7] "potamogeton_friesii"        "potamogeton_gramineus"     
##  [9] "potamogeton_illinoensis"    "potamogeton_natans"        
## [11] "potamogeton_nodosus"        "potamogeton_praelongus"    
## [13] "potamogeton_richardsonii"   "potamogeton_strictifolius" 
## [15] "potamogeton_sp"             "potamogeton_obtusifolius"  
## [17] "potamogeton_alpinus"        "potamogeton_perfoliatus"   
## [19] "potamogeton_epihydrus"      "potamogeton_spirillus"     
## [21] "potamogeton_bicupulatus"    "potamogeton_diversifolius" 
## [23] "potamogeton_hillii"         "potamogeton_vaseyi"        
## [25] "potamogeton_obtusifolius.1" "potamogeton_sp.1"
#alltime max vet depth 
  
  a <- rawdata[ , .("survey_ident"= .GRP, "totnsamp" = .N, "clpN" = sum(potamogeton_crispus >= 1, na.rm = T), "lat_median" = median(latitude, na.rm = T), "lon_median" = median(longitude, na.rm = T)) ,   , .(SURVEY_START, DOW) ][ , clpfoc := clpN/totnsamp ,]
  
  
  #get snow data https://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?mn5435
snow <- fread("scripts&data/data/input/MSP_snowfall_alltime.csv")
  snow
##     Winter_end_year   JUL   AUG   SEP   OCT   NOV   DEC   JAN   FEB   MAR   APR
##               <int> <int> <int> <num> <num> <num> <num> <num> <num> <num> <num>
##  1:            1939     0     0   0.0   1.9   0.5   9.1   7.4  11.0   6.0   3.9
##  2:            1940     0     0   0.0   0.6   0.0   4.8   5.0   9.1  25.6   0.0
##  3:            1941     0     0   0.0   0.0  26.3  10.6   3.3   5.5   6.8   0.0
##  4:            1942     0     0   0.0   0.0   3.8   8.6   1.7   5.2   4.6   0.0
##  5:            1943     0     0   1.7   0.3   0.9   7.0  10.1   4.6   9.8   0.0
##  6:            1944     0     0   0.0   0.0  10.3   0.0   1.0   4.2  11.1   0.3
##  7:            1945     0     0   0.0   0.0   2.5   1.1   8.2  15.4   0.7   6.0
##  8:            1946     0     0   0.0   0.0   4.5  14.6   4.3  11.9   1.5   0.1
##  9:            1947     0     0   0.0   0.0   4.1   5.9   7.6   1.9   3.3   2.0
## 10:            1948     0     0   0.0   0.0  21.8   6.7   3.5  11.6   5.2   0.3
## 11:            1949     0     0   0.0   0.0   2.5   2.3  12.5   3.4   8.3   9.3
## 12:            1950     0     0   0.0   0.0   2.7   6.5  17.0   7.9  11.1   6.4
## 13:            1951     0     0   0.0   0.0   5.6  25.0   7.1   8.6  40.0   2.6
## 14:            1952     0     0   0.0   0.8  10.8  16.5   9.9  15.0  25.4   0.6
## 15:            1953     0     0   0.0   0.0  10.1   6.0   6.0  13.4   6.7   0.7
## 16:            1954     0     0   0.0   0.0   1.9   5.9   3.6   1.0  10.7   0.2
## 17:            1955     0     0   0.0   0.4   6.4   4.0   7.8  11.0   4.3   0.0
## 18:            1956     0     0   0.0   2.5   6.0  14.6   4.6   2.4  14.0   1.1
## 19:            1957     0     0   0.0   0.0   6.8   2.1   4.9   8.7   7.0   9.6
## 20:            1958     0     0   0.0   0.0  10.3   2.2   2.4   1.2   3.5   1.6
## 21:            1959     0     0   0.0   0.0   3.3   2.4   1.4   6.3   5.7   0.0
## 22:            1960     0     0   0.0   3.7   6.9   3.5   9.5   2.7   5.5   0.0
## 23:            1961     0     0   0.0   0.0   2.4   1.7   4.6   8.7  15.1   7.7
## 24:            1962     0     0   0.1   0.0   2.5  18.1   5.9  26.5  21.8   6.4
## 25:            1963     0     0   0.0   0.0   5.6   3.2   5.0   5.4   9.8   5.5
## 26:            1964     0     0   0.0   0.0   0.0   7.6   5.0   1.0   9.7   5.6
## 27:            1965     0     0   0.0   0.0   4.3   8.1  10.5  11.7  37.1   2.0
## 28:            1966     0     0   0.0   0.0   1.6   1.2  11.9   6.8  14.2   0.4
## 29:            1967     0     0   0.0   0.2   3.4  12.7  35.3  23.7   2.6   0.2
## 30:            1968     0     0   0.0   0.3   0.8   2.4  10.6   2.2   0.8   0.4
## 31:            1969     0     0   0.0   0.0   4.9  28.7  21.6   5.3   7.3   0.3
## 32:            1970     0     0   0.0   2.4   3.8  33.2   9.8   4.3   8.6   1.3
## 33:            1971     0     0   0.0   0.0   6.3   5.5  19.9  13.9   7.0   1.9
## 34:            1972     0     0   0.0   0.0  13.4  12.8  12.2   7.6  10.4   8.0
## 35:            1973     0     0   0.0   0.0   1.1  15.3  11.6  11.3   0.4   2.0
## 36:            1974     0     0   0.0   0.0   0.1  17.9   2.5  15.7   7.7   7.3
## 37:            1975     0     0   0.0   0.0   1.2   6.1  27.4   9.0  18.3   2.2
## 38:            1976     0     0   0.0   0.0  16.2   5.6  12.8   5.1  13.6   0.0
## 39:            1977     0     0   0.0   2.3   1.4   8.3  13.4   1.8  14.6   1.8
## 40:            1978     0     0   0.0   3.0  11.7  14.2   6.8   4.6   8.5   1.9
## 41:            1979     0     0   0.0   0.0  16.5  15.1  14.2  13.5   8.4   0.7
## 42:            1980     0     0   0.0   0.0   7.7   1.7  12.9   8.8  13.7   8.5
## 43:            1981     0     0   0.0   0.0   0.9   2.8   4.6  11.0   0.1   1.7
## 44:            1982     0     0   0.0   0.9  14.0  10.6  46.4   7.4  10.9   4.8
## 45:            1983     0     0   0.0   1.4   3.6  19.3   3.2  10.8  14.3  21.8
## 46:            1984     0     0   0.0   0.0  30.4  21.0  10.8   9.3  17.3   9.8
## 47:            1985     0     0   0.0   0.3   2.0  16.3  13.1   4.2  36.8   0.0
## 48:            1986     0     0   0.4   0.0  23.9  13.5  10.3  12.3   8.7   0.4
## 49:            1987     0     0   0.0   0.0   4.4   4.2   5.5   1.2   2.1   0.0
## 50:            1988     0     0   0.0   0.3   4.5   7.5  19.5   4.5   3.7   2.4
## 51:            1989     0     0   0.0   0.2  15.8   7.2   6.0  17.3  22.7   0.8
## 52:            1990     0     0   0.0   0.0  11.3   7.0   1.1  10.7   3.2   2.2
## 53:            1991     0     0   0.0   0.0   5.0  11.7   6.5  14.2   4.4   1.5
## 54:            1992     0     0   0.0   8.2  46.9   6.7   5.0   5.9  10.8   0.6
## 55:            1993     0     0   0.0   1.3  12.2   9.2  12.0   5.3   6.9   0.5
## 56:            1994     0     0   0.0   0.0   7.7   4.5  24.3  12.0   1.7   5.5
## 57:            1995     0     0   0.0   0.0   6.2   6.5   4.2   2.1  10.4   0.2
## 58:            1996     0     0   0.0   0.7   6.6  16.1  14.5   1.2  14.1   2.3
## 59:            1997     0     0   0.0   0.0  16.8  23.7  14.2   4.0  14.3   0.6
## 60:            1998     0     0   0.0   0.0   8.6   3.3  20.4   1.1  11.6   0.0
## 61:            1999     0     0   0.0   0.0   0.1   3.1  33.1   4.2  16.0   0.0
## 62:            2000     0     0   0.0   0.0   0.7   7.3  18.2   7.7   1.0   1.3
## 63:            2001     0     0   0.0   0.0   9.8  30.2   9.4  16.5   8.6   1.3
## 64:            2002     0     0   0.0   0.1   9.4   8.0   9.5   3.1  15.7  20.2
## 65:            2003     0     0   0.0   0.6   1.4   3.0   5.1  10.7  13.2   1.0
## 66:            2004     0     0   0.0   0.0   9.4  16.1  10.7  19.7  10.4   0.0
## 67:            2005     0     0   0.0   0.0   0.5   1.8   8.6   8.0   6.6   0.0
## 68:            2006     0     0   0.0   0.0   5.1  14.5   2.3   2.1  20.4   0.0
## 69:            2007     0     0   0.0   0.0   0.2   4.3   5.5  12.6  11.0   1.9
## 70:            2008     0     0   0.0   0.0   0.4  18.1   2.0   4.8  18.0   1.6
## 71:            2009     0     0   0.0   0.0   4.3  17.4   8.4  10.9   1.5   2.5
## 72:            2010     0     0   0.0   2.8   0.0  20.9   3.1  13.9   0.0   0.0
## 73:            2011     0     0   0.0   0.0   9.8  33.6  17.0  16.1   8.2   1.9
## 74:            2012     0     0   0.0   0.0   3.0   7.3   4.6   6.1   1.3   0.0
## 75:            2013     0     0   0.0   0.0   0.8  15.0   4.6  15.1  13.8  17.9
## 76:            2014     0     0   0.0   0.0   1.1  15.9  22.7  18.4   4.7   7.0
## 77:            2015     0     0   0.0   0.0   9.4   5.6   5.4   4.9   6.8   0.3
## 78:            2016     0     0   0.0   0.0   5.1   9.5   4.1  12.1   5.4   0.5
## 79:            2017     0     0   0.0   0.0   2.3  15.8   8.4   0.3   4.7   0.5
## 80:            2018     0     0   0.0   0.1   0.6   6.4  20.4  15.9   8.8  26.1
## 81:            2019     0     0   0.0   0.3   4.0   6.7   6.8  39.0  10.5   9.8
## 82:            2020     0     0   0.0   0.0  14.3  11.3   9.8   7.5   1.3   7.3
## 83:            2021     0     0   0.0   9.3   8.8  12.4   7.8   5.9   4.0   0.5
## 84:            2022     0     0   0.0   0.0   1.2  21.5  10.5  10.3   5.1   1.6
## 85:            2023     0     0   0.0   0.4  13.0  19.8  22.3  15.5  15.5   3.8
## 86:            2024     0     0   0.0   2.7   0.5   2.1   2.0   7.0  15.2   0.0
##     Winter_end_year   JUL   AUG   SEP   OCT   NOV   DEC   JAN   FEB   MAR   APR
##       MAY   JUN   ANN
##     <num> <int> <num>
##  1:   0.0     0  39.8
##  2:   0.0     0  45.1
##  3:   0.0     0  52.5
##  4:   0.0     0  23.9
##  5:   0.0     0  34.4
##  6:   0.0     0  26.9
##  7:   0.0     0  33.9
##  8:   3.0     0  39.9
##  9:   0.2     0  25.0
## 10:   0.0     0  49.1
## 11:   0.0     0  38.3
## 12:   0.0     0  51.6
## 13:   0.0     0  88.9
## 14:   0.0     0  79.0
## 15:   0.0     0  42.9
## 16:   2.4     0  25.7
## 17:   0.0     0  33.9
## 18:   0.0     0  45.2
## 19:   0.0     0  39.1
## 20:   0.0     0  21.2
## 21:   0.0     0  19.1
## 22:   0.0     0  31.8
## 23:   0.0     0  40.2
## 24:   0.0     0  81.3
## 25:   0.0     0  34.5
## 26:   0.0     0  28.9
## 27:   0.0     0  73.7
## 28:   0.0     0  36.1
## 29:   0.3     0  78.4
## 30:   0.0     0  17.5
## 31:   0.0     0  68.1
## 32:   0.0     0  63.4
## 33:   0.2     0  54.7
## 34:   0.0     0  64.4
## 35:   0.0     0  41.7
## 36:   0.0     0  51.2
## 37:   0.0     0  64.2
## 38:   1.2     0  54.5
## 39:   0.0     0  43.6
## 40:   0.0     0  50.7
## 41:   0.0     0  68.4
## 42:   0.0     0  53.3
## 43:   0.0     0  21.1
## 44:   0.0     0  95.0
## 45:   0.0     0  74.4
## 46:   0.0     0  98.6
## 47:   0.0     0  72.7
## 48:   0.0     0  69.5
## 49:   0.0     0  17.4
## 50:   0.0     0  42.4
## 51:   0.1     0  70.1
## 52:   0.0     0  35.5
## 53:   0.3     0  43.6
## 54:   0.0     0  84.1
## 55:   0.0     0  47.4
## 56:   0.0     0  55.7
## 57:   0.0     0  29.6
## 58:   0.0     0  55.5
## 59:   0.0     0  73.6
## 60:   0.0     0  45.0
## 61:   0.0     0  56.5
## 62:   0.0     0  36.2
## 63:   0.0     0  75.8
## 64:   0.0     0  66.0
## 65:   0.0     0  35.0
## 66:   0.0     0  66.3
## 67:   0.0     0  25.5
## 68:   0.0     0  44.4
## 69:   0.0     0  35.5
## 70:   0.0     0  44.9
## 71:   0.0     0  45.0
## 72:   0.0     0  40.7
## 73:   0.0     0  86.6
## 74:   0.0     0  22.3
## 75:   0.5     0  67.7
## 76:   0.0     0  69.8
## 77:   0.0     0  32.4
## 78:   0.0     0  36.7
## 79:   0.0     0  32.0
## 80:   0.0     0  78.3
## 81:   0.0     0  77.1
## 82:   0.0     0  51.5
## 83:   0.0     0  48.7
## 84:   0.0     0  50.2
## 85:   0.0     0  90.3
## 86:   0.0     0  29.5
##       MAY   JUN   ANN
#convert to cm
  snow[ , names(.SD) := lapply(.SD, function(x){x*2.54}), .SDcols = !c("Winter_end_year")]

#add snow to plant abund data:
  a[ , date := as.IDate(SURVEY_START, format = "%m/%d/%Y") , ]
  a[ , year := year(date) , ]
  
  
  a[snow, on = .(year = Winter_end_year ) , annual_snowfall := ANN]

  a[ DOW %in% a[ ,.N , DOW][N>2, DOW], .N ,  DOW]
##          DOW     N
##        <int> <int>
##  1: 62005500    12
##  2: 62022500    10
##  3: 27071100     4
##  4: 81000300     7
##  5: 80003400     5
##  6:  2000400     8
##  7: 62000600    13
##  8: 40000200     4
##  9: 70002200     7
## 10: 34003200     3
## 11: 27006202     7
## 12: 27009501    14
## 13: 27011700    13
## 14: 27104200     9
## 15: 27104501    10
## 16: 41004300    11
## 17: 27002800    10
## 18: 27004800     8
## 19: 27004500     7
## 20: 70006900     8
## 21: 70009100     3
## 22: 27004400     5
## 23: 27019200    16
## 24:  2000900    13
## 25: 10000200    19
## 26: 27007000    10
## 27: 70005000     4
## 28: 82009999     5
## 29: 82011800    22
## 30: 27010400     5
## 31: 71014500     8
## 32: 71014700     8
## 33: 62001100     4
## 34: 10004401     4
## 35: 10004800    14
## 36: 27018600     5
## 37: 82010100    16
## 38: 82010300    14
## 39: 10001300    24
## 40: 10004402     4
## 41: 27005500     6
## 42: 18024300     8
## 43: 49013300     7
## 44: 77004600     7
## 45: 62000100     5
## 46: 73015100     6
## 47: 10004100     4
## 48: 10008800     3
## 49: 29025000     6
## 50: 13002700     6
## 51: 62007500     3
## 52: 27007100     5
## 53: 27011800     4
## 54:  3010700     3
## 55: 10004200     7
## 56: 19002200     3
## 57: 27007800    17
## 58: 10004500     3
## 59: 62005400     8
## 60: 71001300     6
## 61: 27019101    11
## 62: 62023100    11
## 63: 27019102     9
## 64: 83004300     7
## 65: 47002600     5
## 66: 47003200     5
## 67: 73003700     3
## 68: 10005300     3
## 69: 19002500     5
## 70: 82010400    11
## 71: 27003501     5
## 72: 82016300     7
## 73: 27013300     8
## 74: 10004300     4
## 75: 62004700     9
## 76: 30013500     4
## 77: 27062700     3
## 78: 61000600     3
## 79: 27003502     3
## 80: 62005600     3
## 81: 10000700     4
## 82: 66001800     3
## 83: 62004800     3
## 84: 82010600     6
## 85: 82010900     4
## 86: 10005100     3
## 87: 86013900     3
## 88: 82007400     3
## 89: 82001000     3
## 90: 82010700     3
## 91: 82000400     3
##          DOW     N
  a[ , county := substr(str_pad(as.character(DOW),pad = "0", side = "left", width = 8), start = 1, stop = 2) , ]
  
  all_state <- a
  rm(a)
  
  metro <- all_state[ county %in% c("02", "27", "19", "62", "82", "10" ,"70")  ]

metro[ ,.N , DOW][N>2, DOW]
##  [1] 62005500 62022500 27071100  2000400 62000600 70002200 27006202 27009501
##  [9] 27011700 27104200 27104501 27002800 27004800 27004500 70006900 70009100
## [17] 27004400 27019200  2000900 10000200 27007000 70005000 82009999 82011800
## [25] 27010400 62001100 10004401 10004800 27018600 82010100 82010300 10001300
## [33] 10004402 27005500 62000100 10004100 10008800 62007500 27007100 27011800
## [41] 10004200 19002200 27007800 10004500 62005400 27019101 62023100 27019102
## [49] 10005300 19002500 82010400 27003501 82016300 27013300 10004300 62004700
## [57] 27062700 27003502 62005600 10000700 62004800 82010600 82010900 10005100
## [65] 82007400 82001000 82010700 82000400
metro[ DOW %in% metro[ ,.N , DOW][N>2, DOW] , hist(year) ]

## $breaks
##  [1] 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022 2024
## 
## $counts
##  [1]  2  2  9 25 50 59 79 72 51 73 69 28
## 
## $density
##  [1] 0.001926782 0.001926782 0.008670520 0.024084778 0.048169557 0.056840077
##  [7] 0.076107900 0.069364162 0.049132948 0.070327553 0.066473988 0.026974952
## 
## $mids
##  [1] 2001 2003 2005 2007 2009 2011 2013 2015 2017 2019 2021 2023
## 
## $xname
## [1] "year"
## 
## $equidist
## [1] TRUE
## 
## attr(,"class")
## [1] "histogram"
ggplot(metro[DOW %in% metro[year > 2015 ,.N , DOW][N>2, DOW] & year > 2015, , ] , aes( annual_snowfall, clpfoc), )+
   geom_point()+
   geom_smooth(method = "lm")+
   facet_wrap(~DOW, scales = "free")
## `geom_smooth()` using formula = 'y ~ x'

summary(lm(clpfoc~annual_snowfall, data = metro[DOW %in% metro[,.N , DOW][N>2, DOW], , ]))
## 
## Call:
## lm(formula = clpfoc ~ annual_snowfall, data = metro[DOW %in% 
##     metro[, .N, DOW][N > 2, DOW], , ])
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -0.30789 -0.21291 -0.06681  0.15208  0.71285 
## 
## Coefficients:
##                   Estimate Std. Error t value Pr(>|t|)    
## (Intercept)      0.3344886  0.0324794  10.298   <2e-16 ***
## annual_snowfall -0.0002417  0.0002237  -1.081     0.28    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.2574 on 517 degrees of freedom
## Multiple R-squared:  0.002253,   Adjusted R-squared:  0.0003234 
## F-statistic: 1.168 on 1 and 517 DF,  p-value: 0.2804
plotpanels <- ggplot(metro[DOW %in% metro[ ,.N , DOW][N>2, DOW], , ], aes( annual_snowfall, clpfoc, group = as.factor(DOW)) )+
  geom_point(aes(color = as.factor(DOW)))+
  geom_smooth(aes(color = as.factor(DOW)), method = "lm", se = F)

ggplotly(plotpanels)
## `geom_smooth()` using formula = 'y ~ x'

So, from that plot I’d say the answer is no, a lake manager can’t just use the MSP snowcover to assess effects on CLP.

To do list: - exclude non 7co metro -DONE - run before 2016 - DONE -

Figure for Vignette

# make a background of "all data"

ggplot(metro , aes( annual_snowfall, clpfoc), )+
   geom_point()

ggplot(metro, aes( annual_snowfall, clpfoc) )+
  # geom_point(aes(color = as.factor(DOW)), alpha =.5)+
  stat_smooth(geom='line', method = "lm" ,alpha=0.25, se = FALSE, aes(color = as.factor(DOW)), linewidth = 1.0)+
  theme_bw()+
  guides(color="none")+
  geom_smooth(method = "lm", linewidth = 1.5)+
    scale_y_continuous(name="Curlyleaf pondweed Abundnace") +
  scale_x_continuous(name="Annual Snowfall in Region (cm)")+ 
  theme(axis.text = element_text( size=10),
    axis.title.x = element_text(face="bold", size=15),
        axis.title.y  = element_text(face = "bold", size=15))
## `geom_smooth()` using formula = 'y ~ x'
## `geom_smooth()` using formula = 'y ~ x'

summary(lm(clpfoc~annual_snowfall, data = metro)) # the unfiltered 
## 
## Call:
## lm(formula = clpfoc ~ annual_snowfall, data = metro)
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -0.33227 -0.20975 -0.06528  0.15300  0.72882 
## 
## Coefficients:
##                   Estimate Std. Error t value Pr(>|t|)    
## (Intercept)      0.3659833  0.0291857  12.540   <2e-16 ***
## annual_snowfall -0.0004841  0.0002024  -2.392   0.0171 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.2561 on 627 degrees of freedom
## Multiple R-squared:  0.00904,    Adjusted R-squared:  0.00746 
## F-statistic:  5.72 on 1 and 627 DF,  p-value: 0.01707
summary(lm(clpfoc~annual_snowfall, data = metro[DOW %in% metro[year < 2016 ,.N , DOW][ ,DOW], , ]))
## 
## Call:
## lm(formula = clpfoc ~ annual_snowfall, data = metro[DOW %in% 
##     metro[year < 2016, .N, DOW][, DOW], , ])
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -0.33410 -0.20570 -0.06128  0.15491  0.67803 
## 
## Coefficients:
##                   Estimate Std. Error t value Pr(>|t|)    
## (Intercept)      0.3694089  0.0301921  12.235   <2e-16 ***
## annual_snowfall -0.0005123  0.0002136  -2.399   0.0168 *  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.2488 on 517 degrees of freedom
## Multiple R-squared:  0.01101,    Adjusted R-squared:  0.009092 
## F-statistic: 5.753 on 1 and 517 DF,  p-value: 0.01681
summary(lm(clpfoc~annual_snowfall, data = metro[DOW %in% metro[year > 2015 ,.N , DOW][ ,DOW], , ]))
## 
## Call:
## lm(formula = clpfoc ~ annual_snowfall, data = metro[DOW %in% 
##     metro[year > 2015, .N, DOW][, DOW], , ])
## 
## Residuals:
##     Min      1Q  Median      3Q     Max 
## -0.3124 -0.2023 -0.0663  0.1476  0.7206 
## 
## Coefficients:
##                   Estimate Std. Error t value Pr(>|t|)    
## (Intercept)      0.3451136  0.0338422  10.198   <2e-16 ***
## annual_snowfall -0.0003353  0.0002309  -1.452    0.147    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 0.2506 on 469 degrees of freedom
## Multiple R-squared:  0.004477,   Adjusted R-squared:  0.002355 
## F-statistic: 2.109 on 1 and 469 DF,  p-value: 0.1471
# show two lakes on top, one with increasing and one with decreasing snow relationships

# # decrease w/ snow
# ggplot(a[DOW %in% c("62005400"), , ] , aes( annual_snowfall, clpfoc), )+
#    geom_point()+
#    geom_smooth(method = "lm")
# 
# 
# 
# # increase w/ snow
# ggplot(a[DOW %in% c("82010600"), , ] , aes( annual_snowfall, clpfoc), )+
#    geom_point()+
#    geom_smooth(method = "lm")

So, from that plot I’d say the answer is no, a lake manager can’t just use the MSP snowcover to assess effects on CLP.